There are many therapeutic indications today that pose problems in terms of technique, cost efficiency, or efficacy, or combinations thereof.
For example, following an interventional procedure, such as angioplasty or stent placement, a 5 Fr to 8 Fr arteriotomy remains. Typically, the bleeding from the arteriotomy is controlled through pressure applied by hand, by sandbag, or by C-clamp for at least 30 minutes. While pressure will ultimately achieve hemostasis, the excessive use and cost of health care personnel is incongruent with managed care goals.
As another example, blood leaks from a variety of different tissues are common during surgical procedures. Examples include following trauma to or resection of the liver, spleen, or kidney, vascular anastomoses, and bone bleeding during sternotomy. Presently, the surgeon has a limited number of options to control bleeding, typically pressure, thrombin, fibrin glue, bone wax, and/or collagen sponge.
Likewise, controlling air leaks from lung tissue is difficult to achieve during thoracic procedures. Examples include lung resections and lung volume reduction surgery. Presently, the surgeon has a limited number of options to control air leaks, typically a chest tube is required to remove air from the thoracic cavity. The presence of a chest tube extends the stay of the patient in the hospital. If the air leaks could be sealed at the time of surgery, the patient would be able to be discharged sooner.
Similarly, controlling liquid leaks from tissue is difficult to achieve during surgical procedures. Examples include dural leaks and lymph fluid leaks during surgical procedures. Typically, the surgeon does not control dural leaks due to the lack of an effective dural substitute, potentially increasing the risk of transmission of infectious agents. Controlling solid leaks from tissue is likewise difficult to achieve during surgical procedures. Examples include bowel leaks during surgical procedures. Typically, the surgeon controls bowel leaks by adding additional sutures until the leak is no longer observed.
As another example, adhesions are abnormal, fibrous connections of tissues that are not normally connected. Adhesions are formed as a part of the normal wound healing response of tissue, however they can result in infertility and pain. Several products are available for use by the surgeon to prevent the formation of adhesions, however the efficacy of the marketed products has not been conclusively demonstrated.
Likewise, tissue voids can be created by a variety of procedures. For example, the ABBI™ system, marketed by United States Surgical Company, is a minimally invasive breast biopsy system that cores out breast tissue for analysis by a pathologist. The cores range in size from five to twenty millimeters in diameter. Following the removal of the core, a tissue void is created and the surrounding tissue oozes blood into the void.
Various tissues can also be augmented to create a more desired appearance. For example, an injectable bovine collagen, marketed by Inamed Corporation, can be used to reduce the appearance of facial wrinkles or create the appearance of fuller lips. While the treatment is effective, the persistence is brief.
The treatment of arterio-venous malformations (AVM's) and aneurysms provide further examples. AVM's are tangled masses of blood vessels that are neither arteries nor veins, commonly found in the brain, possibly leading to hemorragic stroke. Clinically, AVM's are treated by surgical removal. Before removal, the AVM must be embolized to prevent uncontrolled bleeding. Aneurysms are abnormal widening of portions of blood vessels, leading to an increased chance of rupture. Clinically, aneurysms are treated by surgical removal, stent-grafting, or coils. Another possible treatment modality is to fill the ballooned section of the blood vessel with a biomaterial, protecting and strengthening the diseased tissue.
There is also an increasing trend towards site-specific delivery of pharmaceuticals and vectors. The main advantage is high dose delivery at the diseased tissue, but a low systemic dose. For example, a depot filled with anti-cancer agents can be placed directly on a tumor. The areas surrounding the depot have a high concentration of the anti-cancer agent, but the systemic dose is low, minimizing side effects.
Cells, as well as pharmaceuticals and vectors, can be likewise delivered to a diseased tissue site. The cells could be genetically modified, autologous, or derived from other sources.
There remains a demand for biomaterials that improve the technique, cost efficiency, and efficacy of these and other therapeutic indications.